By My Side
by Mieko15
Summary: Mattsun and Mari one shots dedicated to the couple becoming canon and cute af. Enjoy their journey together!
1. Chapter 1

After Mari confessed her feelings to Anna and was in obvious hurt, Mattsun was there to comfort her. She requested for him to walk her home that day, which he did, holding the umbrella slightly over her more, sacrificing his back to keep her dry. Through the rain, he could still see the small tear drops near her lower lashes. She was walking one step ahead of him, as usual, and making sure to hide her sadness. Finally he spoke against the loud pitters of rain.

"Hey, don't do that" he said stopping in his tracks.

Wiping the last of her tears she turned around with a puzzled expression.

"Don't do what?" her words became shaky once more.

"You're walking ahead of me...why don't you walk beside me instead" he suggested as he pulled onto her frail hands. She let him move her next to him, enough that their shoulders were hugging.

"There, isn't that better? Now tell me what's on your mind" he continued to walk, this time he intertwined his hands with hers. He still sheltered her side, causing the rain to catch his right shoulder.

She stayed silent, possibly sinking into her own thoughts.

"Actually it's okay, you don't have to tell me. I wouldn't want to become jealous anyway. Hearing you talk about other people romantically, now that get's me flustered", this caught Mari's attention. She only glanced towards the taller man's direction, waiting for him to explain what he meant.

"It's especially hard that someone like Anna, who's smart, kind, and just an amazing person could be my rival" he laughed a little, attempting to warm the atmosphere.

Mari remembered what Natsuki had mentioned before she went to meet with Mattsun.

" _Mattsun's a good guy"._

She squeezed his hand a little making him jump, afraid she was going to claw him in a second.

"Don't…" she began. "Don't think that you're not great…You may have a stupid ego, and you're a creepy guy, but you're not a bad guy" she said, just loud enough for him to hear through the rain. "You're a good guy Mattsun".

Mattsun was taken aback, a bit shocked that she would even say such kind words through venomous ones. But somehow a smile still seemed to creep up his face.

"Good enough to be your boyfriend?" he managed to joke while turning his face to her.

Like the tsundere she was, Mari just gave a glare in his direction.

"You're lucky my hands are cold" she mumbled.

"Ah, so that's the reason why you won't let go of me" he laughed as her face turned an obvious shade of red. From laughing to serious, Mattsun kissed the top of her forehead while she wasn't looking.

"Just stay by my side okay? I promise you won't hate it" he smiled.

That day, Mari let Mattsun walk her home without a scratch on his face. She even managed to give him a hug before he dropped her off at her house.

A/N: How was the first opening chapter of my Mattsun x Mari one shots? I love Nijiro Days and this is my fave couple. Let me know if you want more one shots! Until the next chapter ^^


	2. Chapter 2

Mari brushed her hair as she stared straight into the mirror. Her thoughts hadn't left her mind about Mattsun. As much as she wanted to hate him she couldn't. Her thoughts came to a halt as she heard the ringing of her phone. Glancing over, she realized it was the number she finally managed to save in her contacts.

"What do you want" her voice came out hoarse and stern.

A chuckle filled the other end. "Good morning to you too."

Mari left an unsettling pause as a reply.

"You gonna let me inside? Or am I gonna be forced to wait in the cold with these bags of treats."

Mari stood up and headed to the front door of her apartment. Every Sunday Mattsun would manage to make his way over just to see her. Although she didn't show it, it made her feel so happy to see him outside of school. Opening the door, she stood small in front of the red headed male.

"Living room is to the right" she said turning her back from the man. Mattsun was amazed as he stepped inside. Never had he been allowed to come inside her house. Now and then he would get a few glances inside when he dropped her off, but other than that he was always forced to wait outside.

"What a change of heart" he whispered to himself as he placed the box of desserts onto the living room table. On the table laid out several magazines, each with beautiful models with glamorous looks. When turning back he realized she brought cups of tea she prepared from the kitchen.

"I didn't deem you the type to like fashion" he laughed while sifting through the different articles.

"I was thinking about trying something different...maybe with my hair" she exclaimed while setting the tea down. Mattsun glanced back at her, catching a few strands of hair into his hands. It slipped so easily through his fingers.

"Oh? What inspired you to? Ayye did Anna put you up to this?" he asked half heartedly.

"Why? Are you jealous?" she challenged him.

Mattsun shook his head, "I like your hair a lot. But if you want to make a change to it, by all means be my guest". He held several pictures in his hand this time, facing it in her direction.

"Which one?"

Mari gulped her tea down, a bit embarrassed.

"Maybe this?" she asked pointing towards the shorter haircut, one that showed off her forehead.

"You'd look good in anything" he laughed while ruffling her front bangs. This caused Mari to blush a little to herself. The warmth of course caught Mattsun's attention.

"Ah, it's so cute how you're not used to my touch yet" he laughed while placing his right hand against her cheek.

"You're such a weirdo" she said stubbornly, swiping his hands away. "Don't flatter yourself, it's cold."

Mattsun gave a smirk before sitting himself next to her.

"What are you doing?" she demanded as he wrapped his arms around her forcing both bodies to fall to the floor. Holding her against his chest, Mattsun intertwined his hands through her hair.

"As much as I say you'd look beautiful in anything, I'm really gonna miss this hair" he muffled into her hair.

Giving in, Mari wrapped her arms around his lower waist. "I won't cut it then" she whispered back.

"What's that?" he asked a bit taken back. Mattsun was already distracted by the voluntary touch she gave.

"I said I won't cut it" Mari said, this time lifting her head so he could see her eyes. "I won't dye it, I won't do anything".

"Are you doing this just to please me?" he laughed while inching his way close to her face.

"Stop saying weird things" she spat back.

"Hair is hair Mari-chan~" he stated simply without an explanation.

With that, the two remained still in each other's arms. Though it was freezing cold outside, there was a warmth that grew from a single living room in the apartment.

A/N: Awww did you see the way he held her? Well I mean, I guess you can't physically see it, but awwww.


	3. Chapter 3

Mattsun was waiting near the front door of his complex. His eyes couldn't keep off the clock as he checked several times. His little sister had gone on a date with his good friend Kei and he couldn't bring himself to just let her come home late with him. It was 10 minutes past the time she said she was going to return. Like the protective big brother he was, he waited thinking about the things he would say when she came home.

Without another second, the door began to jiggle. Unlocked, the door pried open revealing Nozomi with Keiichi behind her.

"You're still up?" she asked a bit shocked to see Mattsun waiting like a father in the living room. Without a hint of sympathy he stated "You're late. I couldn't sleep knowing you were out at night with Kei" he stated.

Kei on the other hand, unphased at all, just laughed and walked Nozomi further into the house.

"Don't worry Mattsun, I didn't do anything to her" he said while patting her shoulder.

"I had a good time okay? We should hangout again sometime" Kei stated, this time only towards Nozomi.

Nozomi, being the lover she was, sprang to life and nodded.

Just before Mattsun could interfere, he received a call. Taking his phone out from his pocket he examined the contact slowly.

"Anna? Why would she be calling me so late?"

As soon as the call came through he jumped into action, grabbing a jacket and sprinting out the door.

"Don't do anything while I'm gone" he shouted down the hall towards the two lovers left in the house.

"Thank you for coming at such a late hour" Anna said with a relieved expression. "She's had a bit too much to drink...we were celebrating my promotion and I think she exceeded her limit because of stress" Anna claimed while directing him in the direction of the dark haired female.

Glancing over Anna, Mattsun could see Mari on her "who knows what number" shot of sake.

"Alright spit woman, party's over" he laughed trying to lighten the mood. Mari only glanced at him as he placed his arms around her waist, lifting her to stand.

"Who the hell are you" she slurred her words.

"Idiot, I'm your boyfriend" he said spacing his words so she could understand.

"Oooooooh Matttt-suuun" she said poking his forehead. "I'm fine I'm fine", clearly she wasn't.

He managed to pick her up bridal style which was difficult at first since she was kicking and screaming to come down. But once he walked outside, her shrieks turned to shivers as she clung to him for warmth.

"See you later Anna, I'll call you when we reach her house" he said while propping her in place.

(Who knows how long it took them to get to her house realistically. But for the sole purpose of this story let's just say it wasn't that long)

Once he got into her house, he carried her towards her bedroom. Mari, being intoxicated as hell, was still drunk. He called Anna like he promised, and made sure Mari was drinking enough water to sober her up.

"What was so stressful that caused you to drink this much?" he asked while lying next to her on the bed. He didn't expect her to answer, but she did.

"I'm struggling in school"

"So am I, but you don't see me getting shit faced" he teased, one hand holding up his own head, the other comforting her. She was still cute even when she was drunk, he thought to himself.

"Mattsun…" she said in a sweet soft voice. It caught his attention, especially since he was used to her throwing venom with his name.

"I'm here" he assured, brushing her hair once again.

"...I miss you a lot" she slurred silently at first, and then her words became louder. "I get jealous of those girls who come around! Don't they know you're mine?!" she stammered. Her drunk frustration entertained him.

"Oh? This is the first time I'm hearing this" he laughed.

She only nodded her head (she couldn't hold herself up straight). "You're so good to me…" she said resting her face closer to his.

"I know I know" he said proudly. "You should open up to me more like this when you're sober" he laughed while cuddling her small body into his arms. Nuzzling her head through his arms she smiled.

"Kiss me"

"What?" he shot back so fast. Don't get him wrong, he wasn't complaining. But he hadn't kissed her since the first day they met.

This time she said it more shyly. "Kiss me".

"Mari-chan, you're a little drunk right now" he laughed, making a joke that she was actually a lot drunk right now. "Ask me in the morning when you're feeling better" he said sitting up, but of course he was pulled back down.

"I'm asking you now~" she chimed.

"Why do I have to initiate?" he smirked. Stunned, Mari began pouting, something he wasn't used to seeing.

"Fine". Instead of giving up, she took him by surprise, placing her hand against his face and kissing him. Once they broke away Mattsun could barely function. Her lips were soft and plump, leaving a small essense of sake he could taste. His face was red as a tomato, thank god for the darkness.

"There. Maybe now they'll stop" she stated confidently. It took him a few moments to realize she was referring to the girls at school.

"Dummy, they're not here right now" he smiled while tapping her head lightly.

"I know...thank you…" she said, this time her words became lighter as she became sleepier.

"I love you Mari~" he cooed into her ear.

Unfortunately she was so tired that she passed out against his chest, unable to hear him.

 _Ayyy, why does this girl put me in these kinds of situations!_

He screamed in his head as he was still flustered.

 **A/N: I'm screaming lmao they're so cute I cry! Wowowow I posted two back to back real quick. I felt that my last one shot wasn't enough lol. Don't mind me as I write at 2am, getting inspiration as I sit in bed hahaha. More to come in the next few Mattsun x Mari oneshots. Let me know how it is! :-)**


	4. Chapter 4

Mari was towered over by the taller man as she managed to keep pace with him. It was poorly lit enough that no one could see the figures. His hands cupped her cheeks as he continuously kissed her lips. Breathless kisses filled the air until she stopped him and covered her mouth embarrassed.

"This is the last time" she stubbornly claimed while backing away from the man. They were in front of her door to her apartment and like clockwork he was never allowed inside after their late night dates.

"You said that the last time" he snickered while giving the woman a smirk. "It's not like your brothers around, I'm sure he won't mind if I stayed the night" he hinted while nudging her lightly.

Mari rolled her eyes before she spoke, "Don't get any ideas Mattsun, I've only recently been okay with...doing that" she said blushing harder as she referred to their make-out session. He nodded, surprisingly Mari was being very generous the past couple of weeks. Never did he think he'd be kissing, let alone dating the girl of his dreams.

"I promise I won't get weird," he said holding his hand up to show his honesty. "I just want to sit on the couch and watch a movie with my girlfriend. Is that so difficult to ask for?" he spoke sweetly.

"Yes. I'm tired" she said unlocking the door and almost slamming it in his face. Catching the door with his foot (ouch), he propped the door open. "Curse your boy strength" she swore under her breath. "Mattsun I just wanna sleep" she repeated again. Letting go he nodded.

"Okay, okay, fine. Goodnight Mari-chan" he said softly while allowing her to close the door. Pausing for a moment she stared at her empty apartment and sighed as she realized how dark and empty it was. "Dammit" she whispered to herself before opening the front door.

"One movie that's it" she said while catching the man heading towards the stairs. Mattsun gave a small smile as he approached Mari.

"You don't even like romcoms" Mattsun laughed as he pulled Mari in closer. They were sharing a blanket leaned up on one side of the couch. It was true, Mari didn't believe relationships came to be like they did in romantic comedy movies, but she knew that Mattsun enjoyed them a lot. "I don't hear you complaining" she punched him in the gut, light enough that he could reply.

"Hey now, don't get mad at me because you're actually enjoying me staying over" he teased while putting her head on his chest. Mari showed no response, but he knew she was incredibly grateful.

"I'm so comfortable I could fall asleep right now" he joked while slouching further into the couch. "I have work tomorrow," Mari said killing his comfy mood.

"Easy. I'll just set an alarm and walk you there before I catch my train" he said already placing alarms on his phone. Mari let out a scoff. "You're something Mattsun. Boldly staying over like you planned this" she said yawning in between her words. He nodded, "Now where were we earlier" he laughed pulling her in for another kiss.

"Talking about how I have work tomorrow" she smirked ruining his smooth transition.

"You play hard to get too much" he laughed while inching in for another butterfly kiss. But before the butterfly could even land he heard snoring from the girl below him. She had already knocked out in his arms. "Geez, she wasn't kidding when she said she was tired" he laughed while placing his hands on his forehead in defeat.

Picking her up, he took her to her room where he covered her in blankets and shut the door behind him as he returned to the living room. "Well looks like it's me and the couch tonight" he sighed before taking his place on the couch. Another night spent at Mari's.

 **A/N: I'm so MIA it hurts. Idk I just write as I go I guess. Sorry this might not be the best everyone was expecting since I haven't updated in a year. But prays that I'll continue to find the inspiration from the manga like I did for this one. Thanks loves!**


	5. Chapter 5

Mari rolled over in her bed feeling a lump form in her throat. No way was she getting sick, she thought. Groaning, she managed to reach her contacts on her phone. Waiting for the short ring on the other end, a voice answered almost instantly.

"Hello? What's up?" the voice belonged to her older brother.

"Maa-kun, I've come down with a cold...do you think you can help me out?" she asked pleading. She hadn't seen her brother in weeks and missed his company.

"Ahh...you see, I'm actually out of the city right now. My wife and I are in Tokyo for vacation" he exclaimed sighing. "Please update me though, I'll call later tonight when we get back to our hotel" he promised before she hung up. She hesitated a moment before calling her next choice. Her finger hovered over the contact before pressing it, waiting for an answer.

"Mari-chan~" the voice echoed through the room, even when it was not on speaker.

"I'm sick..." she said coldly while letting a few coughs slip in.

"Sick?! So what you're saying is you want me to come over" the voice chuckled. She could practically hear his smirk through the phone.

"Calm down, my brother isn't around that's all, and I have no one else to call. Don't flatter yourself," she said stubbornly.

"Mari-chan I'm hurt. You don't have to phrase it that way." Mattsun said. She could feel his pouting. It was amazing how easy she could sense his emotions.

"Just get me some medicine!" she shouted while breaking a sweat. "I think I have a fever" she calmed, this time her voice sounded more tired.

* * *

Mattsun arrived, bag in hand of all sorts of items. She had left the door unlocked so she wouldn't have to get up when he came. There he found her lying in bed with a towel placed on her head.

"Oi, Mari-chan, take your medicine before you pass out," he said while bringing her medication and some water by her bedside. Sititng up the best as she could she managed to consume it.

"Thank you" she said softly before lying back down. Mattsun sat beside her, placing his hands on his cheeks as he watched the girl. Her eyes were closed and her face was red, sweat running in all directions of her face.

"I'd appreciate it if you didn't stare so deeply at me," she said, feeling his stares.

"I can't help it okay," he said smiling. "It's rare to see you being so tame and dependent towards me" he laughed while brushing her forehead.

She didn't reply for she was in between being tired and agitated by the heat. "How long do you want me to stay?" he asked, knowing how annoyed she grew of him from time to time. Feeling her hand reach up to grab is, he became startled. Knowing how she felt he smiled, hiding his blushing with his other hand.

"I'll stay as long as you need me to," he said clenching her hands tighter.

* * *

The following week Mari grew better overcoming her cold. It wasn't until she received a call back in the morning.

"Hello?" she asked getting ready to leave her home.

"Um...this is embarrassing...but I think I caught your cold" Mattsun explained while coughing. "If you don't mind I'd really appreciate it if-"

"I'll be there in a bit" she cut his words off. Mattsun gave a small laugh, one that held love. He wasn't used to Mari being this accepting. Maybe somewhere inside she felt a little bad that he had caught her cold and wanted to repay him for taking care of her.

* * *

"What'd I tell you about the staring," Mari said clenching her teeth together as she sat by Mattsun's side. She was in the middle of changing the towel on his forehead when she caught the man staring right at her. He smiled while making contact with her hands. She, of course, pulled away, turning to get him water. By the time she turned back to pas the man the glass of water, he was half naked.

"Put a shirt on" she demanded, her words struggled to come out.

Mattsun was oblivious to his action, "Oh...it's really hot though and this fever is boiling me alive" he stated while brushing off the clothing to the side. Mari attempted to cover her cheeks, she was embarrassed and taken off guard by the man.

"Then go under the blankets" she stammered while tossing a blanket over the man. Removing it off at once he let a chuckle escape his lips. "This isn't the first time you've seen a man without a shirt on right? Because that would downright hilarious" he joked, trying to make her face his direction.

"Actually, yes...not counting my brother after all," she said avoiding his eyes.

"Mari look at me" he laughed while holding her hands.

"It's okay, the ground looks lovely from here" she joked. Rolling his eyes he used all the strength he had left to pull her against his body. Still flustered, she buried her face into his sweaty body.

"I'm gonna get sick again" she shouted into him as her words became mumbled by skin.

"It's okay, it's worth it to see you" he whispered under his breath.

"WHAT?!" she exclaimed almost kicking the man.

"I said, I might vomit on you" he laughed before getting socked in the face by her elbow.

* * *

 **A/N: Aw my babies are so cute together. Hope you guys are enjoying these little one shots! I also love seeing the feedback and reactions you guys give. It means a lot that people love this couple and give love to this series.**


	6. Chapter 6

Mattsun slumped on the couch, crossing his arms in jealousy. The school festival had finished and in the midst of the festival was a woman and man auction for charity. The event took place in the gym where students could bid money for a date with an individual that was placed on the stage. Coincidently Mari's homeroom was assigned the position to be auctioned off. And someone bid $500 to go on a date with Mari. Mattsun was not pleased when he found out a first-year bidded on her.

"Come on Mattsun, it's just one night and it's for a good cause," Mari said pulling at the man's arm.

"No I'm upset" he pouted while letting go of her hand. Rolling her eyes Mari tried to reassure him again.

"Don't get mad at me. I didn't know someone was gonna bid high or at all for me. Besides I'm your girlfriend remember? It's not like he's going to steal me from you" she laughed while grabbing hold of his face. Mattsun melted a little but had to show he was still angry.

"Could you at least dress down...you don't have to wear makeup and do your hair you know?" he said, this time with more envy.

"The man paid $500, you'd want the best if you were paying for a date with a girl" she stabbed the words into him. "I know it sounds bad selling yourself for a night, but nothing will happen, trust me," she said calmly.

"Actually now that I think about it, why didn't you just outbid the guy, then you'd have a nice dinner with me and spend your money for charity," she said poking her nose in his direction. Mattsun didn't answer for a while. The truth was that he was too broke to outbid the rich first year. Shamefully he gave in.

"Don't worry, I'll be back before you know it" she exclaimed while grabbing for her purse and exiting his house.

* * *

Without Mari knowing Mattsun still decided to come along with. He placed a poor disguise on himself by wearing a beanie and hiding with sunglasses and a dark trench coat even though it was super hot in the summer. He was aware of what restaurant they'd beat and even managed to get himself a table for one. Of course, he ordered a small meal for him as his main goal was to watch over the date. Seeing his girlfriend and the first-year across the way he tried to listen to their conversation.

"You look lovely Mari~" the man said while guiding her into her seat.

"Thank you for being a gentleman" she praised while taking her seat. Browsing over the menu allowed for the man to make conversation.

"I didn't think I'd imagine being here with you Mari. It means a lot. I heard so much about you from the sports teams like how you subbed in for that injured player. That was incredibly kind of you to do such a thing" he said in admiration. Mari nodded. She had never thought of it as something so nice it was enough to want to go on a date with someone.

"So I know you're somewhat still new to this school. What is your interest?" she asked nicely. Mattsun couldn't stop slamming his fist on the table. _That was unnecessary questions to ask Mari-chan. Who cares about this guys interest?_ he yelled in his head.

As the night grew on Mattsun couldn't help but grow more and more jealous. The man was intentionally hitting on Mari without a care. Trying to touch her arm and hold her hand across the table. He even sang to her a little, something Mattsun for sure couldn't do too well.

* * *

After their dinner, Mari and the man walked the streets. It was darker this time and he offered to buy her ice cream as an end of the night treat. Of course, she said yes to sweets. Mattsun, of course, followed a block behind the two.

As they stood on a bench licking their soft serve ice cream the man started to become even bolder than before. He placed an arm around Mari, keeping their faces semi apart from one another. Mari was unphased.

"You got some ice cream on your face Mari" he exclaimed while taking his thumb and trying to brush it off her lips. This riled up Mattsun even more.

"Thanks..." Mari could only say, a bit flustered since she normally didn't let anyone touch her, especially another guy.

"I had a great time tonight, and I really do think you're a wonderful girl Mari," he said this time lingering near her lips. "That's it" Mattsun was about to jump on the guy but before he could pursue further Mari pushed the man away.

"I'm sorry, you're a sweet dude, but I do still have a boyfriend, and I love him very much," she said giving the two space.

"If you have a boyfriend why did you even agree to go on this date?" he asked a bit hurt. Mari sighed. "I thought it was a nice thing for charity. Besides, you didn't really think that something real would come from a date you bid on right?" she asked a bit concerned for the man.

"I suppose...well I'm sorry to disrespect you like that. I still had a great time while it lasted" he mumbled. Before Mari could comfort a man a voice shouted from behind the two.

"Mari-chan!~" the man waved his arms while rushing towards the two.

"Mattsun? What the hell are you doing here?" she said to herself while squeezing the skin between her eyebrows.

"I'm here to pick you up after your date" he exclaimed acting as if he wasn't stalking the couple.

"Were you following us the whole time? I told you you'd have nothing to worry about" she stated while placing her hands on her hips.

"Don't worry, it's okay senpai. If I was your boyfriend I too would be overprotective" the first year announced while backing away. "You should go" he said while shyly looking to the floor.

Mattsun already had his arms around Mari's guiding her in the opposite direction.

"I'm sorry! You were a really good date though" she managed to call out to the boy before disappearing into the dark.

* * *

"Spit woman. I should make you jealous next time. Maybe I'll go out with a girl to make you feel the way I felt" Mattsun shook his head while still heated about the situation.

"Don't you dare" she said giving him a dark look. "If you do, be prepared to not see me for months," she said sternly. Knowing how much Mattsun was clingy she knew he would give in.

"Fine...but only because you love me" he stated sternly before letting out a giggle. Her head snapped back towards him.

"You heard that?" she said upset but simultaneously glowing red.

"Of course...I love you too" he managed to say while holding her close to his side. The two walked close in each other's arms the rest of the night home.

* * *

 **A/N: The faves awww they are jealous of each other but still manage to work things out! This weeks chapter is up!**


End file.
